Malignancies in patients with AIDS are being recognized as an increasing problem worldwide. Furthermore, although generally effective, HAART therapy is not curative, and is associated with significant toxicity. Therefore, potential complementary approaches to treatment, including gene therapy, are actively being evaluated. Currently, the options for non- toxic viral vectors capable of stable integration, long term transgene expression, and transduction of quiescent cellular targets, including HSCs, is very limited. We and others have previously demonstrated that recombinant vectors based upon the non-pathogenic parvovirus, adeno- associated virus (AAV), can stably and safely transduce murine and human hematopoietic progenitors (HPCs), in vitro and in urine HPC transplant and xenograft models in vivo. Furthermore, we have shown that CD4+ cell lines and the monocyte-macrophage progeny of primary CD34+ cells transduced with rAAV vectors encoding RNA transcripts designed to inhibit HIV-1 replication exhibit long term protection for subsequent HIV-1. We hypothesize that transplantation of autologous CD34+ progenitors transduced with rAAV vectors encoding HIV inhibitory RNAs can safely result in multi-lineage engraftment, and protect otherwise HIV susceptible cells in HIV infected individuals. In this proposal, we will utilize an active, ongoing clinical protocol for the treatment of AIDS associated Non Hodgkin's Lymphoma (NHL), and address several issues which are critical to the development of rAAV vectors for human gene therapy. These include: (1) Safety of transplantation of rAAV transduced HPCs in a clinical trial, (2) the stability of rAAV transduction and transgene expression in primary CD34 cells and their progeny, and their ability of transduced CD34 cells to give rise to multi-lineage engraftment in vivo, and the determination of the potential for in vivo protection of the progeny of HPCs transduced with rAAV vectors anti-HIV transcripts in a clinical trial (3) and in parallel murine SCID/hu xenograft model (4). The ability of the SCID-hu model to predict clinical outcome will also be assessed. Finally, we will employ genetic "marking" and sensitive PCR sensitive PCR assays to determine whether residual tumor cells in the graft contribute to clinical relapse after ASCT (5). These studies will form the basis for improved treatments for autologous HSC transplantation for lymphoma and HIV infection, and will provide seminar data for the use of rAAV vectors for gene therapy for hematopoietic progenitors.